The present invention relates generally to hermetic hard disk drives comprising integrally molded filters and related methods.
A disk drive is a device used to store information in a computing environment. In a disk drive, data is generally recorded on planar, round, rotating surfaces (which are commonly referred to as disks, discs, or platters). There are several types of disk drives, including optical disk drives, floppy disk drives, and hard disk drives. Nowadays, hard disk drives tend to be most common. Strictly speaking, “drive” refers to a device distinct from its medium, such as a tape drive and its tape, or a floppy disk drive and its floppy disk. A hard disk drive (sometimes referred to as a HDD), also referred to as a hard drive, hard disk, or fixed disk drive, is a non-volatile storage device that stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Early hard disk drives had removable media; however, a HDD today is typically an encased unit with fixed media.
A typical hard disk drive includes a head disk assembly (HDA) and a printed circuit board assembly (PCBA) attached to a disk drive base of the HDA. The HDA typically includes at least one magnetic disk, a spindle motor for rotating the disk, and a head stack assembly (HSA) having an actuator assembly with at least one transducer head, typically several, for reading and writing data from the disk. The PCBA includes a servo control system in the form of a disk controller for generating servo control signals. The HSA is controllably positioned in response to the generated servo control signals from the disk controller. In so doing, the attached heads are moved relative to tracks disposed upon the disk. The heads are typically distanced from the magnetic disk by a gaseous cushion—so that they are said to “fly” over the disk. Thus, it is important that the position of the heads be well-controlled for proper reading and writing from the disk.
Hard disk drives are generally sealed to prevent dust and other external sources of contamination from interfering with operation of the hard disk heads therein. Some hard disk drives are hermetically sealed (i.e., they are “hermetic hard disk drives”). A hermetic seal is generally understood to be an airtight seal. Note that some seals (e.g., those “sealing” air within the hard disk drive) are not literally air tight, but rather utilize an extremely fine air filter in conjunction with air circulation inside the hard drive enclosure. The spinning of the disks causes air to circulate therein, forcing any particulates to become trapped on the filter. The same air currents also act as a gas bearing, which enables the heads to float on a cushion of air above the surfaces of the disks. However, “hermetically” sealed means that the seal is so airtight that the disk drive's internal pressure is substantially independent of the external or ambient pressure. This is in contrast to a conventional or non-hermetically sealed disk drive that has a breather port with a filter in a wall of the base plate or cover for equalizing the disk drive's internal pressure with the external pressure. Thus, a hermetically sealed drive does not contain a breather port.
Hermetic hard disk drives are first filled with a desired gaseous medium (whether it be atmospheric air or one or more other gases) before operation. Within a hermetically sealed hard disk drive, gases other than atmospheric air are often employed. Filling the sealed environment of a hard disk drive with gases other than air can enhance their performance. For example, use of lower density inert gases, such as helium, can reduce aerodynamic drag between the disks and their associated read/write heads by a factor of approximately five-to-one as compared to their operation in air. This reduced drag beneficially results in reduced power requirements for the spindle motor. A helium-filled drive, thus, uses substantially less power than a comparable hard disk drive operating in an air environment. At the same time, the helium gas also conducts heat generated during operation of the disk drive away more effectively than air.
Hermetic sealing generally aims to protect a hard disk drive from problems arising based on events and/or materials external to a disk drive. However, other problems may arise based on events and/or materials internal to a disk drive. That is, design of components within conventional disk drives can contribute to hard disk drive failure. For example, plastic components are susceptible to outgassing and components made from conductive materials are prone to shedding of particles, both of which can cause catastrophic disk failure.
Therefore, particulate filters have been incorporated within hard disk drives to help entrap problematic particles and prevent hard disk failure. A common approach to incorporation of such filters in hard disk drives is adherence of a filter to the interior surface of a hard disk drive cover using an adhesive. For example, such filters are described in U.S. Pat. No. 7,630,169 and are commercially available from Donaldson Company, Inc. (Minneapolis, Minn.), including Adsorbent Label Filter (ALF) and an Adsorbent Pouch Filter (APF) forms. Nevertheless, alternatives to use of adhesives for such applications are desired.
In view of the number of potential problems impacting effective and long-term performance of hard disk drives, alternative methods and apparatus for improved hard disk drives are desired. Most desired are those methods and apparatus with improved efficiency and reliability over conventional attempts to provide the same.